Devices for detecting the presence of wetness and/or liquid leaks have a number of applications including in mechanical systems having liquid lines or in experimental protocols or devices in laboratories or in use with those having enuresis or incontinence or those undergoing blood treatments. In particular, it is important to detect wetness due to blood leaks or other liquid line leaks during procedures that involve the removal of blood from a person, procedures like blood donation, blood detoxification, blood filtration/hemofiltration and hemodialysis. In hemodialysis, for example, blood is removed from a patient through a needle into a blood liquid line circuit that carries the blood to a hemodialysis machine that filters out waste toxins and removes excess water from the blood. With blood normally removed from the patient and through the blood liquid line circuit at a rapid rate, dislodgement of the needle or a break in the blood liquid line would lead to rapid and potentially fatal blood loss. For this reason, hemodialysis, which generally takes several hours and must be performed several times a week, is typically done in a medical setting where patients can be supervised. Patients must constantly be monitored visually by medical personnel for blood leaks so that, if needle displacement occurs, it can be identified and remedied before detrimental blood loss takes place.
Many devices have been proposed to detect wetness due to urine or blood or to detect the disconnect of a needle from a patient or a break/leak in a liquid line; however, these devices have several drawbacks. For example, many of the wetness detectors are not particularly efficient and, therefore, are mostly ineffective. Thus, they require too much moisture and/or liquid to trigger an alarm or there is too long of a delay between the occurrence of the wetness and the detection and/or alarm of the wetness. In the case of hemodialysis, these deficiencies could be deadly; quick detection and alert is necessary in order to minimize blood loss due to the disconnect of a needle or a leak in a liquid line. Further, many proposed or existing devices are uncomfortable, unwieldy and, in the case in which an electric circuit is used to detect the moisture, can be unsafe if the patient is not properly protected from the electric circuit. Importantly, many devices are not appropriate to detect blood leaks that occur during extracorporeal blood treatments as the devices either can not distinguish between blood and other bodily liquids or do not do so adequately. Consequently the devices trigger a number of false alarms, a situation that substantially reduces the usefulness of the devices in a medical setting. In addition, many of the known wetness detection devices can not themselves be physically reused, nor are their detection systems designed to be reset after wetness and/or moisture has been encountered.
Thus, there is a need for a wetness detection system that can rapidly detect wetness due to liquid leaks and accurately identify any wetness that may be due to blood, especially in the instance of extracorporeal blood treatments. What is required is a detector that is sensitive enough to detect a small amount of moisture in order to trigger an alert of a liquid leak. There would also be benefit to a wetness detection system that could monitor a number of wetness sensors simultaneously and one that has a number of different alarms at its disposal to alert both users and, where appropriate, medical personnel of blood and/or liquid line leaks. In the case of hemodialysis, this would free medical personnel from having to visually inspect a number of patients for blood leaks due to needle displacement or blood line breaks, allowing them to focus on other tasks. Further, it would be advantageous for the wetness detector to be able to be reused and the wetness detector system be easily reset after wetness has been detected and/or an alarm has occurred.